Thursday, May 01, 2008

In class today, I referred to a recent report on very fast rates of evolution in allochtonous Italian wall lizards (Podarcis sicula) introduced from a neighboring island to the Croatian island of Pod Mrcaru in 1971. It appears that, on top of outcompeting the indigenous lizard population, they have undergone extremely rapid morphological change in less than 40 years, evolving new gut adaptation (i.e., cecal valves, to slow down the passage of food through the gut, to favor digestion of plant matter) and a squatter, more robust skull better suited to chewing plants, which constitute the main source of lizard food on the island. The report, perhaps a bit exaggeratedly, refers to this as "fast track evolution."

The rapid physical evolution also sparked changes in the lizard's social and behavioral structure, he said. For one, the plentiful food sources allowed for easier reproduction and a denser population.

The lizard also dropped some of its territorial defenses, the authors concluded.

Such physical transformation in just 30 lizard generations takes evolution to a whole new level, Irschick said.

It would be akin to humans evolving and growing a new appendix in several hundred years, he said.

"That's unparalleled. What's most important is how fast this is," he said.

Neat stuff. The report includes some cautionary statements by a McGill biology professor (Andrew Hendry), but overall's he seems on board with the gist of the study. The article version of the study can be found by clicking here, and some good comments were provided on several blogs, including Pharyngula and GrrrlScientist.